1. Field of the Invention
The invention relates generally to submersible pumps for use in oil field operations. In particular, embodiments relate to methods and apparatuses for moving fluid through one or more stages of an electrical submersible pump.
2. Background Art
Pumping systems driven by motors are used to extract or move fluid and gas. In subsurface operations such as in a wellbore environment, typically electric submersible pumping (ESP) systems are used in the production of hydrocarbon-based fluids. Unlike conventional motors in surface operations, a motor used in a submersible pumping system needs to be submersed in well fluids. The submersible motor is sealed from surrounding well fluids by a motor protector.
A submersible pumping system in the prior art (U.S. Patent Application Publication No. 20050074331) is illustrated in FIG. 1. The pumping system 100 is located within a wellbore 102 in a geological formation 104 containing fluids such as oil. The wellbore 102 is protected with a casing 106 having perforations 108 through which fluids flow from formation 104 into the wellbore 102. The pumping system 100 includes a centrifugal pump 110 having an intake 112, a submersible motor 114 and a motor protector 116. The system 100 is suspended within the wellbore 102 by a deployment system 118. A power cable 120 provides electric power to the submersible motor 122. When pumping, wellbore fluids are introduced into the intake unit 112, and are passed into an intake on the centrifugal pump 110, and out to a tubing string for discharge to the earth's surface.
In FIG. 1, the pump section 100 is located above the motor section 114. Other configurations of pumping systems also exist. For example, a charge pump section may be connected ahead the centrifugal pump 20 in a tandem configuration. ESP systems can also have a pump section located below a motor section.
In addition to using a pump to pump oil to the surface, a centrifugal pump can also be positioned in a wellbore in an inverted position to pump fluids downhole, e.g., during wellbore cleaning.